(1) Field of the Invention
The invention relates to a current supply arrangement, in particular a current supply arrangement for a reactor for producing polysilicon with the Siemens process, with a first current supply device,                with a second current supply device comprisingat least two AC current regulators and avoltage sequence controller for controlling the AC current regulators,        with a terminal group comprising at least two terminals for connecting at least one load, of which terminals a first terminal is connected directly, i.e., without an interconnected switch, with an output terminal of the second current supply device, and        with a first switching means group associated with the terminal group and having switching means for connecting and disconnecting the terminals of the terminal group with or from output terminals of the first current supply device.        
(2) Description of Related Art
A current supply arrangement of this type is disclosed in the published German patent application having the publication number DE 10 2009 021 403 A1 as well as in the utility model document DE 20 2009 003 325 U1. The current supply arrangements described in these documents are used in reactors for producing polysilicon with the Siemens process or by chemical gas deposition. The first current supply device of the described current supply arrangement provides an intermediate voltage (1 to 30 kV nominal voltage), which can be applied to the thin silicon rods at the beginning of the deposition with the Siemens process. Supply of current can then be taken over by the second current supply arrangement after ignition of the rod pairs. The second current supply device includes several input terminals and several AC current regulators. The input terminals are connected to different electrical potentials which may be provided, for example, at the secondary-side taps of a transformer. The voltages supplied by the transformer are in the low-voltage range (0 to 3 kV nominal voltage). The AC current regulators of the second current supply device are each connected, on one hand, with a respective one of the input terminals and, on the other hand, with the output terminal. The AC current regulators are implemented as thyristor regulators. However, regulators with other converter valves can also be used. The AC current regulators are controlled by a sequential voltage controller. A sequential voltage controller is described, for example, in previous applications of the applicant, and also in the book “Thyristorized Power Controllers” by G. K. Dubey, S. R. Doradla, A. Joshi and R. M. K. Sinha. The voltage supplied by the second current supply device is a low-voltage.
The aforementioned publications are directed to current supply arrangements supplying electric power to four loads, i.e., four rod pairs. Reactors for the Siemens process have recently been designed for significantly more than four rod pairs. Reactors designed for 24 rod pairs have been disclosed. A current supply arrangement for a reactor with 24 rod pairs is known, for example, from the published utility model DE 2007 001 083 U1. However, the current supply arrangement disclosed in the utility model does not have a first current supply device which supplies the rod pairs with an intermediate voltage at the beginning of the deposition process. The current supply arrangement disclosed in DE 2007 001 083 U1 has several second current supply devices supplying electric energy to the rod pairs. These rod pairs are arranged in groups and at least one second current supply device is associated with the groups. The rod pairs within the group are connected in series at the beginning of the deposition process and are later connected in parallel. Switching means are provided for switching between a series connection for supplying power to the rod pairs and a parallel connection. The current supply device disclosed in the utility model publication DE 2007 001 083 U1 is quite complex due to the required switchover between the parallel operation and the series operation of the rod pairs.
This is a starting point for the present invention.